Mastadon had a similar issue with it’s larger servers before the blowup. It’s sadly not possible to stop in a completely open source and federated service. By design, anybody can join in, and create a new instance to do with as they please

If you want to make it better we need more servers that block this trash, and who have larger user-bases than the current ones. Create quality content on reasonable instances, advertise these sites, and bring other creators in